A rapid development and low cost requirement of a cable wideband access technology promote a development of gradually replacing an existing copper (cable) system with optical fiber, that is, exit of copper and development of the optical fiber have become a trend. Simultaneously, with broadest, fastest and most environmentally friendly features of PON, and with features of a long-distance PON having a structure for a flat and simplified network, and advantages such as adaptation to a network structure with a long distance, reduced investment cost and the like, PON is being accepted by most operators and starts to or is ready to be deployed, in order to satisfy gradually increased communication users and demand of the users for faster and better service.
A long-distance PON is a point-to-multipoint optical fiber access technology. FIG. 1 shows a structure diagram of a long-distance passive optical network in the prior art, and as shown in FIG. 1, the long-distance passive optical network includes an Optical Line Terminal (OLT), an Optical Network Unit (ONU) and an Optical Distribution Network (ODN). Generally, one OLT is connected with multiple ONUs through a light reach extender box (also called long-distance box) and a light power separator (short for optical splitter) to form a point-to-multipoint structure.
In order to reduce investment cost and achieve multiplexing of ODN, several PON systems (hereinafter referred to as coexisting PON system) may share one ODN in a passive optical network. FIG. 2 shows a structure diagram of a coexisting long-distance passive optical network, as shown in FIG. 2, as different PON systems, such as, a PON system with coexistence of such two kinds of PONS: a GPON and an XG-PON, generally have different uplink and downlink wavelengths, wherein the downlink wavelength of a GPON is 1480 nm-1500 nm and the uplink wavelength of the GPON is 1290 nm-1330 nm, while the downlink wavelength of an XG-PON is 1575 nm-1581 nm and the uplink wavelength of the XG-PON is 1260 nm-1280 nm, the two PON systems can share one ODN through a WDM1r wavelength division multiplexing filter, as shown in FIG. 2, the long-distance box in the prior art is mainly designed for a single-PON system, for a system in which multiple PONS coexist, long-distance boxes for a single-PON system cannot be used for such the system in which the multiple PONS coexist, therefore a synthetic long-distance box is required to satisfy such demand.